Wearable Defibrillators In Ischaemic Cardiomyopathy: Bridging The Gap

Sudden cardiac death remains a major concern after myocardial infarction, particularly when left ventricular systolic function is severely reduced. An implantable cardioverter-defibrillator (ICD) can lower mortality in appropriately selected patients, yet the indication is often time-dependent. Ventricular function may improve after revascularisation and guideline-directed medical therapy, while early implantation can expose some patients to avoidable device complications.

A wearable cardioverter-defibrillator (WCD) occupies this uncertain interval. It continuously monitors the rhythm through surface electrodes and can deliver a high-energy shock without requiring an invasive procedure. In people with ischaemic cardiomyopathy, it may provide temporary protection while clinicians clarify recovery, arrhythmic risk, comorbidity, and long-term treatment preferences.

The device is not a substitute for an ICD in a patient with a persistent indication, nor is it a universal response to a low ejection fraction. Its value depends on careful patient selection, reliable wear time, rapid clinical follow-up, and a shared understanding of what the device can and cannot do.

For Australian electrophysiology services, the question is especially relevant across different care settings. A patient treated in Melbourne or Sydney may have rapid access to imaging and device review, whereas someone in regional Queensland, Western Australia, or the Northern Territory may face long travel for fitting, troubleshooting, or reassessment. A temporary external strategy can help bridge that logistical and clinical gap when it is used within a structured pathway.

Why The Waiting Period Matters

After an acute coronary syndrome, ventricular function can change substantially over several weeks. Reperfusion, revascularisation, beta-blockade, renin–angiotensin system inhibition, mineralocorticoid receptor antagonism, sodium-glucose cotransporter 2 inhibition, and management of congestion may all influence ejection fraction and symptoms. A low measurement early after infarction therefore does not always represent a permanent substrate.

Primary-prevention ICD decisions usually require a waiting period after myocardial infarction and revascularisation, alongside optimisation of medical therapy and reassessment of left ventricular function. The exact timing depends on the clinical scenario and current guidance. During this window, some patients remain at meaningful risk of sustained ventricular tachycardia or ventricular fibrillation.

Risk is not captured by ejection fraction alone. The infarct burden, myocardial scar, recurrent ischaemia, nonsustained ventricular tachycardia, syncope, autonomic factors, renal disease, heart failure severity, and adherence all influence the assessment. A WCD can offer interim protection while these factors become clearer, but it should be prescribed as part of an active plan rather than as a holding pattern without review.

Selecting Patients For Temporary Protection

The clearest candidates are patients with a transiently high risk of malignant ventricular arrhythmia and a reasonable expectation that the long-term decision may change. This can include selected patients with newly diagnosed ischaemic cardiomyopathy and severely reduced ejection fraction, those early after infarction or revascularisation, and people temporarily unable to receive an implanted device because of infection or another procedural contraindication.

A WCD may also be considered after explantation of an infected ICD, during a period of deferred implantation, or when recovery is expected but uncertain. The decision should account for frailty, cognitive function, manual dexterity, hearing, health literacy, social support, and the ability to respond to alarms. A technically suitable patient who will rarely wear the vest has little practical protection.

The device is less compelling when there is no plausible pathway to recovery, when a definitive ICD is clearly indicated and can be implanted safely, or when goals of care exclude shocks. It is also poorly suited to patients who cannot operate the response buttons, tolerate the garment, or engage with follow-up. Shared decision-making should cover discomfort, false alarms, sleep disruption, skin problems, the possibility of inappropriate therapy, and the emotional burden of anticipating a shock.

What The Evidence Shows

Clinical evidence for WCDs is strongest in selected high-risk populations and remains more nuanced for routine primary prevention after myocardial infarction. The randomised VEST study did not demonstrate a significant reduction in arrhythmic death in the intention-to-treat analysis, although adherence was imperfect and secondary analyses have continued to inform debate. Observational registries generally report successful termination of ventricular arrhythmias, but they are vulnerable to selection bias and differences in follow-up.

The central lesson is that efficacy depends on exposure. A WCD can detect and treat a rhythm only when it is being worn correctly, with electrodes positioned appropriately and the monitoring unit active. Wear-time data should therefore be reviewed as a clinical measure, not treated as an administrative detail. Missed hours may reflect poor fit, anxiety, work requirements, bathing, heat, or misunderstanding of the device.

Australian practice also needs to consider access and funding. Availability may vary between public hospitals, private cardiology groups, metropolitan centres, and rural referral networks. A device supplied through a local programme or distributor may involve case-by-case approval, and clinicians should clarify the current Therapeutic Goods Administration status, institutional governance, and payment arrangements rather than assume uniform national coverage.

Fitting, Training, And Daily Use

Effective initiation begins with a practical fitting session. Patients and carers should learn how to wear the garment, charge the monitor, replace or maintain batteries as applicable, respond to alarms, and contact the clinical team. They should understand that pressing the response buttons during a conscious false alarm can inhibit a shock, while losing consciousness removes that option. Emergency services should still be called when a shock occurs or symptoms suggest an acute coronary syndrome.

Daily life requires realistic counselling. The vest generally needs to be removed for bathing, and it must be used in accordance with manufacturer instructions around water and physical activity. Australian summers can create sweating, skin irritation, and adherence problems, particularly for patients in Brisbane, Darwin, or inland communities. Plans for laundering, spare garments, travel, and overnight charging should be agreed before discharge.

Driving deserves explicit documentation. Restrictions after myocardial infarction, syncope, ventricular arrhythmia, or a defibrillator shock are governed by Australian medical fitness-to-drive standards and the patient’s state or territory licensing framework. A WCD does not remove those restrictions. The treating cardiologist should provide clear advice and record it, especially when a patient drives for work or lives far from public transport.

Managing Alarms And Inappropriate Therapy

Alarm education can reduce panic and unnecessary emergency presentations. The patient should know the difference between a warning caused by poor contact, an artefact, a detected fast rhythm, and a therapeutic sequence. Electrode displacement, muscle activity, loose clothing, electromagnetic interference, and sinus tachycardia can complicate detection. Remote monitoring and timely review of stored episodes help distinguish true ventricular arrhythmia from artefact.

The clinical team should also review programming, medication, electrolytes, ischaemia, and device logs after any significant alarm or shock. A patient who receives therapy needs urgent assessment, even if symptoms resolve. Recurrent alarms may indicate a correctable fitting problem, atrial arrhythmia, worsening heart failure, or an emerging need for definitive electrophysiological intervention.

The mechanisms behind device-related shocks deserve the same careful attention given to implanted systems. This review of inappropriate shock mechanisms provides useful context for discussing sensing errors, supraventricular rhythms, and the differences between external and implanted defibrillation strategies. WCD counselling should reassure patients without implying that every shock is either harmless or diagnostic of sudden cardiac death.

Linking The Vest To Definitive Care

A WCD pathway should have a defined review date, usually coordinated with repeat echocardiography and clinical assessment after revascularisation and medical optimisation. Cardiac magnetic resonance imaging may help characterise infarct scar in selected patients, while ambulatory monitoring can identify recurrent ventricular or atrial arrhythmias. The decision at reassessment may be ICD implantation, continued observation, device discontinuation, or referral for another intervention.

Long-term rhythm management may involve catheter ablation, particularly when recurrent ventricular tachycardia or a competing atrial arrhythmia complicates heart failure care. Ablation is anatomy-dependent and should be planned by an experienced electrophysiology team; technical considerations are illustrated in this guide to challenging CTI anatomy. Although cavotricuspid isthmus ablation addresses typical atrial flutter rather than ventricular tachycardia, the broader principle is important: anatomical variation and procedural goals must be matched carefully.

A WCD should never delay urgent revascularisation, treatment of decompensated heart failure, correction of electrolyte disturbances, or management of sustained ventricular arrhythmia. It is a bridge between decisions, not a replacement for them. At every review, clinicians should ask whether the patient’s risk, recovery trajectory, and preferences still support wearing the device.

Building An Australian Care Pathway

A practical Australian model links the implanting or prescribing cardiologist with heart failure nursing, electrophysiology, cardiac rehabilitation, emergency services, and the patient’s general practitioner. Discharge documentation should include the indication, intended duration, contact details, alarm instructions, driving advice, and the date of reassessment. Telehealth can support rural follow-up, but it cannot replace every physical fitting, skin assessment, or echocardiographic review.

Hospitals should establish a process for patients who present to emergency departments with alarms or shocks. Staff need access to manufacturer guidance, device data, and an electrophysiology contact. This matters in smaller hospitals where clinicians may encounter a WCD infrequently. It is also important to consider privacy and data governance when remote monitoring information is transmitted across providers, particularly within shared-care arrangements.

The broader evidence base continues to evolve through registries, health-economic analyses, and studies of high-risk subgroups. Clinicians and trainees can follow current research, educational material, and publication developments through the Journal of Arrhythmia resources. Careful local auditing of wear time, shocks, emergency presentations, complications, and eventual ICD decisions can help Australian services determine where the technology delivers genuine value.

Use wearable defibrillation selectively, explain it precisely, and attach every prescription to a documented reassessment plan. For patients with temporary vulnerability after an ischaemic event, that disciplined approach can provide meaningful protection while recovery and long-term arrhythmia management take shape.